While the Clock has come to represent the level of a number of global threats, including global warming and emerging technologies, the Bulletin attributed this year’s warning almost entirely to the urgent and growing risk of nuclear war.

North Korea’s rapid development of a serious nuclear capability and the “hyperbolic rhetoric” by both Donald Trump and Kim Jong-un topped the list of concerns. Deteriorating relations between the US and Russia, an accelerating nuclear arms race between India and Pakistan, and tensions in the Middle East, the Asia-Pacific region, and elsewhere, contributed to the Bulletin’s assessment that “the world security situation [is] more dangerous than it was a year ago—and as dangerous as it has been since World War II.”

The collapse of US diplomatic leadership under the Trump administration came up for particular criticism. “Neither allies nor adversaries,” the Bulletin said, “have been able to reliably predict US actions—or understand when US pronouncements are real, and when they are mere rhetoric. International diplomacy has been reduced to name-calling, giving it a surrealistic sense of unreality that makes the world security situation ever more threatening.”

Trump’s impending Nuclear Posture Review, the Bulletin added, “appears likely to increase the types and roles of nuclear weapons in US defense plans and lower the threshold to nuclear use.”

The Bulletin called the new Treaty on the Prohibition of Nuclear Weapons “a symbolic victory for those seeking a world without nuclear weapons and a strong expression of the frustration with global disarmament efforts to date.” The ban treaty, of course, is much more than a symbol, but the Bulletin is certainly right when it says that “increased reliance on nuclear weapons, threats, and doctrines that could make the use of those weapons more likely stands in stark contrast to the expectations of the rest of the world.”